W. A. Norton—Coggia’s Comet. 177 
the two branches of the normal tail, in connection with an anom- 
alous curvature of the first portion of the longer branch, when the 
comet was viewed from certain positions of the earth relative to 
the plane of the orbit, observed in the case of Comet II, 1862, and 
elaborately discussed by Prof. Schiaparelli and Prof. Bredichin. 
n this case we have only to suppose that the sun was vertical 
to points of one of the hemispheres, and as a consequence the jet 
discharges were mostly confined to that hemisphere. The longer 
branch of the tail was composed of jets issuing from the lower 
latitudes, while the less copious and more fluctuating discharges 
of matter subject to a diminished solar repulsion (p. 176) from 
r. 
The anomalous curvature of the former system of jets, and their 
interlacing with the other system, was a simple consequence of 
the greater intensity of the solar repulsion in operation on the 
former than on the latter. 
e curious phenomenon of the oscillation of jets first observed 
by Bessel in the head of Halley’s comet, and of which he offered 
in explanation the improbable hypothesis of a polar attractive 
force exercised by the sun upon the nearer portion of the nucleus, 
planes of different local meridians on the nucleus. As the planes 
* To illustrate, if the outstreaming were perm Be right perpen we (Fig. 
: : : us 
thoes easing Pe ress oc oul oor 
Am. Jour. Sci.—Tuirp Serres, Vou. XV, No. 87.—Maxcu, 1878. 
12 
£. 
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